The synthesis of polyesters from phenols, carboxylic acids, and/or phthalates is well-known in the art.
U.S. Pat. No. 4,459,384, issued to Matzner et al, discloses a process of forming a polyester or polyester carbonate in the presence of processing aids. A sulfone may be used as one of the processing aids. The polyester can be prepared by reacting bisphenol-A with mixtures of terephthalic and isophthalic acids.
U.S. Pat. No. 4,123,420, issued to Kyo et al, discloses an aromatic copolyester obtained from a mixture of terephthalic acid and/or functional derivatives thereof and isophthalic acid and/or functional derivatives thereof (with the terephthalic acid/isophthalic acid unit mole ratio being about 9:1 to about 1:9) and a bisphenol of the following general formula: ##STR1## wherein --X-- is selected from the group consisting of --O--, --S--, --SO.sub.2 --, --SO--, --CO--, an alkylene group containing 1 to 4 carbon atoms, and an alkylidene group containing 1 to 4 carbon atoms, and R.sub.1, R.sub.2, R.sub.3, R.sub.4, R'.sub.1, R'.sub.2, R'.sub.3 and R'.sub.4, which may be the same or different, each represents a member selected from the group consisting of a hydrogen atom, a chlorine atom, a bromine atom and an alkyl group containing 1 to 4 carbon atoms, or functional derivatives thereof.
Known methods for producing an aromatic copolyester include, for example, an interfacial polymerization method which involves mixing an aromatic dicarboxylic acid chloride dissolved in a water-immiscible organic solvent with an alkaline aqueous solution of a bisphenol, a solution polyermization method which comprises heating a bisphenol and an acid chloride in an organic solvent, and a melt polymerization method which comprises heating a phenyl ester of an aromatic dicarboxylic acid and a bisphenol, e.g., as disclosed in U.S. Pat. Nos. 3,884,990 and 3,946,091.